Method for securing an elongated metal member to a flat metal sheet



June 2, 1970 E. G. BECK. JR T 3,514,834

METHOD FOR SECURING AN ELONGATED METAL MEMBER To A FLAT METAL SHEETFiled 001;. 5, 1967 2 Sheets-Sheet 1 EFL ea a 30 3o 7 3| 20 I6 I ["11131 3| 3 '32 3a A v10 5 0 -12 3 FIG. I I3\ 33 3' FIG. 3

lNVENTOR/S 64 EDWARD G. BEQK JR.

ATTORNEYS June 2, 1970 E G. BECK, JR 3,514,834

METHOD FOR SECURING AN ELONGATED METAL MEMBER TO A FLAT METAL SHEETFiled Oct. 5, 1967 2 Sheets-Sheet 2 FIG. 6 I0 F|G.7 FIG.8

FIG. 9 72 INVENTOR/S EDWARD e. BECK, JR.

ATTORNEYS United States Patent Int. Cl. B21d 53/02 US. Cl. 29-1573 11Claims ABSTRACT OF THE DISCLOSURE A method of securing metallic tubingand the like to a fiat metal sheet while maintaining the flatness of thesheet so that the composite tube and sheet may be used as radiantheating or cooling panels in building interiors where distortion orwrinkling of the flat sheet would be undesirable. The apparatuscomprises a heating station where a composite of sheet, of suitablydisposed bonding material, and a piece of tubing in properly assembledrelationship and under pressure are heated to induce a bond between thetubing and the sheet while maintaining the sheet in flat condition. Anassembly station is provided including a jig in which the piece oftubing may be accurately located, means for accurately locating the jigwith respect to the sheet, and means for raising and lowering the jigand for releasing the jig from the raising and lowering means so that itmay move with the assembly from the assembly station to the heatingstation. After the heating cycle, the assembly moves to a coolingstation (which may be the same as the assembly station) for a coolingcycle. A combined assembly and cooling station may be provided on eachside of the heating station, each assembly station having a jig wherebyproduction may be speeded up.

CROSS REFERENCE TO RELATED- APPLICATION This application is acontinuation-in-part of copending application Ser. No. 523,619, filedJan. 28, 1966 in the name of Edward G. Beck, Jr. and bearing the sametitle as the present application and now abandoned.

BACKGROUND OF THE INVENTION The invention relates to the field ofradiant heating and cooling panelS. In such panels one face of the panelis exposed in the room or other space which is to be heated or cooled.The unexposed face of the panel is provided with tubing through which aheating or a cooling medium may be circulated to heat or cool the panelby which the room is then either cooled or heated by radiation to orfrom the panel. The invention more specifically relates to an apparatusfor producing such composite panels and to a method of achieving a goodbond in good heat exchange relationship between the panel and the tubingwithout destroying the flatness of the sheet.

Prior attempts to bond a tubing to a flat metal sheet for the abovedescribed purpose have not been satisfactory. In some cases the heatexchange relationship between the tubing and the plate was not good andin other cases where a good heat exchange relationship was achieved, thepanel was distorted so that the configuration of the tubing on the rearface of the panel could be seen on the exposed face of the panel. Theappearance of the panel has not been of critical importance insituations where such panels have been used because primarily they havebeen used in refrigeration evaporators and the like where appearance isnot a primary consideration. How- 3,514,834 Patented June 2, 1970 ever,where the radiant panel is to be a wall panel or a ceiling panel in aroom in a building, no ripples or undulations in the face of the panelshould be apparent even when it is vie-Wed from a very flat angle.

SUMMARY The invention contemplates, from the method standpoint,providing on the sheet a strip of a bonding material in the region wherebond is desired, said bonding material having a lower melting point thanthe sheet and the tube, then accurately locating the tube in contactwith the bonding material, clamping the sheet, over the area which isnot occupied by the tube, under a uniform pressure, maintaining theassembled parts accurately in position while heating the assembly of thesheet, bonding material,

and tubing to a temperautre above the melting point of the bondingmaterial but below the melting point of the sheet and the tubing, andthen cooling the assembly at a relatively high temperature but below thehardening point of the bonding material until the bond has beenachieved.

From the apparatus standpoint, there is provided preferably a centralheating station and on each side thereof and in alignment therewith acombined assembly and cooling station. At each of said stations there isprovided a flat block of metal having a flat upper surface, and thesurfaces of the blocks are in the same horizontal plane. The blocks areof a metal which will not distort at the temperatures encountered at therespective stations. A thin metallic belt of good heat conductivity isdisposed to pass over the said three blocks and means are provided toreciprocate said belt backward and forward. At each of the assemblystations means are provided for raising and lowering a jig which isdetachably secured to the raising and lowering means. The jig comprisesa flat plate of a material which will not distort at the temperatures towhich it will be subjected, and has secured to its underside a block ofnon-metallic material having relatively poor heat conductivity, butsufficient mechanical strength to retain its physical integrity withoutdistortion at the temperatures which will be encountered, The jig willhave at least the same dimensions in the horizontal plane as the sheetto which the tubing will be assembled. The underside of the non-metallicblock will'have one or more grooves of a width sufficient to accommodatethe tubing or other member which is to be secured to the sheet, andthese grooves will be of a depth greater than the thickness of themember to be secured to the sheet. Within the groove or groovesresilient means are provided which will exert pressure against themember in the groove to urge it against the sheet when the jig ispositioned on the sheet.

The bonding material may be a solder either in the form of a ribbon orwires, or in the form of a metallic powder which may be applied to thesheet very accurately by screen printing. The bonding material may alsobe one of the thermosetting resin adhesives. Means are provided inconnection with the jig to'insure accurate location of the tubing in thejig so that the tubing will be assemblied in accurate relationship tothe bonding material disposed on the sheet. Thus, when the jig islowered into contact with the sheet and disconnected from the loweringdevice, the belt moves the assembly to the heating station to create thebond, and thereafter the belt moves the assembly to the cooling stationwhich may be at the same point as the assembly station and may,therefore, be provided with means for heating to a temperature below thehardening point of the bonding material.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a somewhat diagrammatic viewin elevation of an apparatus according to the present invention.

FIG. 2 is a fragmentary plan view of one of the assembly stations.

FIG. 3 is a bottom view of the jig.

FIG. 4 is a fragmentary cross sectional view taken on the line 4--4 ofFIG. 3 but inverted so as to be right side up.

FIG. 5 is a fragmentary elevational view as seen from the right of FIG.3.

FIG. 6 is a cross sectional view through the assembly of jig, tubing,and sheet as disposed on the belt at the assembly station as seen on theline 66 of FIG. 3.

FIG. 7 is a plan view of a template for insuring the proper location ofthe bonding material where it is in the form of strips of solder.

FIG. 8 is a plan view of screen for applying the solder if it is in theform of a powdered metal solder or other material susceptible to screenprinting; and

FIG. 9 is an enlarged fragmentary cross sectional view taken on the line99 of FIG. 8.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1 the heating stationis indicated at B and assembly and cooling stations are indicated at Aand C. At each station there is provided a flat block of uniformthickness with flat top and bottom surfaces, as at 10, 11 and 12. Theseblocks are of a material which will not have its flatness distorted attemperatures encountered during the operations which will be conducted.While these plates may be an annealed steel, they are preferably made ofcast aluminum tooling plate such as manufactured and sold by AluminumCorporation of America as No. 300 Cast Aluminum Tooling Plate. It willbe seen that the upper surfaces of plates 10, 11 and 12 are in a commonplane and a belt 13 is arranged to pass over them. The belt 13 must havegood heat conductivity and may be of perforated aluminum having athickness of .032 inch. In FIG. 1 an assembly 14b is shown at theheating station in broken lines, while another assembly is beingassembled at assembly and cooling station A. At 14c there is shownanother assembly which has cooled down and is about to be removed fromthe assembly and cooling station C.

In order to insure that the tubing or other element to be joined to thesheet is located on the sheet in its proper location, and that the sheetis confined by a uniform pressure over substantially its entire surface,a jig 14 is provided as best seen in FIGS. 3 to 6 inclusive. This jigcomprises a plate 17 which is also preferably a cast aluminum toolingplate as described above, and may have a thickness, for example, of oneinch. Secured to the plate :17 by means of bolts 18 is a block 19 of anon-metallic material which has relatively poor heat conductivity butsufiicient mechanical strength to retain its physical integrity withoutdistortion at soldering, brazing or polymerizing temperatures. By way ofexample, the block 19 may be made from asbestos fiber and an inorganicbinder such as is available from Iohns-Manville Corporation under theregistered trademark Maranite. This material has a density of 65 poundsper cubic foot and by way of example the block 19 may have a thicknessof one inch.

The underside of the block 19 is provided with the groove or grooves 20.In the particular embodiment shown, the groove is sinuous or S-shapedsuch that a previously bent piece of tubing may lie in the groove 20.The width of the groove 20 is such as to accommodate comfortably thetubing 15 and its depth is greater than the diameter of the tubing 15.Within the groove 20 means are provided to urge the tubing against thesheet when the jig is laid on the sheet and these means may be a strip21 of a resilient material which will maintain its resilience at thetemperatures encountered as, for example, a silicone rubber compound ofdurometers. It will be understood that the thickness of the strip 21 isgreater than the difference between the diameter of the tube 15 and thedepth of the groove 20. Instead of the strip 21, stainless steel springmembers may be used. The springs will of course be made of anappropriate alloy which will retain its spring properties at theoperating temperatures of the process. They perform the same function asthe resilient strip 21.

The tubing 15 is accurately located and held in the jig by means ofpressure pins 60. The pins 60 slide in holes in blocks 63 secured to theplate '17 and may be actuated in any desired manner as, for example, byair cylinders, to advance the pins 60 into contact with the tubing, andwhen air pressure is released the springs 61 will serve to retract thepins 60 out of the way. Preferably the pins engage the tubing centrallyof the convex loops as shown in FIG. 3.

Since FIG. 3 is a bottom view and the jig is actually disposed as seenin FIG. 1, additional means may be provided to prevent the tubing 15from falling out of the jig. This is accomplished as shown in FIG. 5 bymeans of the sliding retainers 64. These are simply plates secured tothe block 17 by means of bolts 65 passing through a slot 66 so that theplate 64 may he slid back and forth. They are provided with a finger 64awhich engages under the ends of the tubing 15 where they emerge from thegroove 20.

Each of the jigs 14 is rigidly connected to a shank 34 which is slidablein a guide tube 35 fixedly mounted to a frame member or the like 35a.Means (not shown) are provided to raise and lower the jig 14 and itsshank 34 with respect to the guide tube 35; and when the jig 14 has beenlowered onto the sheet 16, the jig 14 may be disconnected from the shank34. It will be observed that the shank 34 fits snugly into a collarrigidly secured to the jig 14, and is releasably secured thereto by apin 81. The shank fits snugly in the guide tube 35, and is provided witha longitudinal groove 82 which is engaged by a key 83 fastened in theguide tube 35, to prevent rotation of the jig when it is raised. Thuswhen the pin 81 is withdrawn, the shank 34 may be raised without the jig14, which remains on the sheet as shown at station B.

The bonding material may be applied to the sheet before the sheet isplaced on the assembly block in a number of ways depending upon thematerial of the bonding agent. If the bonding agent is a ribbon ofsolder, use may be made of a template 66 as shown in FIG. 7. Thetemplate 66 will be provided with slots 67 and this template 66 isexactly the same size as the sheet. Thus, when the template is laid onthe sheet with its edges coinciding therewith, the strips of solder maybe laid in the slots 67. The slots will be slightly wider and slightlylonger than the strip so that the strip of solder will be easilyaccommodated therein. The solder strips may be coated with a flux whichis quite viscous and sticky at room temperature but becomes relativelyfluid when it is heated. Therefore, the fiux may be heated before it isapplied to both sides of the solder strips 22. Now when these fluxcoated strips are laid on the sheet 16 in the space provided in thetemplate 66, they quickly cool so that the flux again becomes viscousand sticky and effectively adheres the solder strips to the sheet 16 sothat they will not move out of position when the sheet is picked up andmoved to the assembly station.

If the configuration of the panel is such that the strips of solder 22are quite long, difiiculty will be encountered because of the fact thatsolder in ribbon form is usually characterized by camber so that it isdifficult to locate it in the slot 67. Therefore, a preferred way ofapplying solder is by screen printing. In FIGS. 8 and 9 there is shown ascreen comprising a thin sheet of metal 70 having the same width andlength as the sheet 16. Slots 72 are provided through which the bondingagent is to pass and a layer of wire mesh 71 is bonded to the sheet 70.This screen is placed on the sheet 16 with the edges coinciding and apaste of solder and flux is forced through the mesh of the screen 71where the slots 72 permit it and thus films of solder-flux paste aredeposited on the sheet in proper position. It will be understood thatother bonding agents which are initially in paste form may be applied tothe sheet by screen printing.

It will now be clear that having applied the bonding material to thesheet 16 in a predetermined accurate position and knowing that thetubing will be accurately positioned by means of the jig 14, it is onlynecessary to insure that the sheet with the bonding material appliedthereto will be accurately positioned at the assembly station.

The sheets which are ultimately formed into panels by a fiangingoperation will have the cut out corners or notches 36. For the purposeof positioning the sheet at the assembly station, locater arms 30 areprovided which are secured to members 31 so that they may be adjusted,and the members 31 in turn are rotatable with the shaft 32 which ismounted in the base 33. With the locater fingers 30 in the positionshown at Station A in FIG. 1, the sheet 16 is pushed against the fingerswhich engage in the notches 36. The fingers 30 are then rotated out ofthe way so that the jig 14 may be lowered. Thus, it is now assured thatwhen the jig 14 is lowered onto the sheet bearing the bonding material22, the tubing will be precisely located with respect to the sheet andthe strips of bonding material.

As a solder there may be used a composition of 91 percent tin and 9percent zinc with a flux available from Aluminum Corporation of Americaunder the name of Alcoa No. 62. This solder may be positioned in stripor ribbon form or in the form of wire. As pointed out above, a powderedsolder-flux combination may also be used. It is to be understood thatthe word strip as used in the claims is intended to cover a bondingmaterial regardless of its nature or its specific physical form. Ifsolder is used in the form of a ribbon, the tubing 15 lies upon theribbon. If it is in the form of wire, the Wire is laid in such mannerthat the tubing engages wire on one or both sides of the tubing.

In the particular example illustrated, the flat sheet member is of athickness of .040 inch and is of aluminum. The tubing is of copper,having a half inch inside diameter and a wall thickness of .028 inch.The Weight of the jig is sufiicient to apply to the sheet 16 an averageunit pressure of approximately 0.14 psi. The heating station is heatedby any desired means so that the block 11 will attain a temperature ofabout 510 F. This temperature is above the melting point of the bondingmaterial but below the melting point of the sheet and the tubing and ofcourse the belt. It may be desirable at the heating station to increasethe unit pressure to about 4 0.65 p.s.i. by placing additional weight ontop of the jig. With the type of solder described, the assembly is heldat Station B for approximately three minutes. The bonding agent willform fillets between the tubing and sheet on both sides of the tubing asclearly seen in FIG. 6. If the solder is in Wire form, the tubing is ofcourse pressed against the sheet rather than on top of the ribbon andwhen the solder melts it flows in and forms fillets on both sides of thetubing in the same way. Good wetting can be obtained and the assemblywill be ready for cooling after about three minutes.

It is critically important to control the temperature at which thebonding material is cooled in order to avoid wrinkling or distortion ofthe sheet 16. There is a maxi mum difference in temperature between theheating block 11 and the cooling blocks and 12 beyond which distortionor wrinkling of the sheet 16 will probably be experienced. This maximumdifference must be determined for each combination of sheet material andthickness, and tubing material and size. Actually, therefore, thestations A and C are also heating stations in that the blocks 10 and 12are heated. For the particular conditions herein described, they areheated to a temperature of about 300 F. With the particular solder andmaterials described herein, the solder will solidify in approximatelytwo minutes with blocks 10 or 12 at stations A or C at a temperautre ofabout 300 F. At this time, the solder will have developed sufficientphysical properties that the assembly may be removed from the machine.Before removal, of course, the members 64 will be Withdrawn.

It will be noted that from the time the jig is assembled over the sheet,the sheet 16 is tightly confined over its entire area except for thegrooves 20, between the bottom face of the non-metallic block 19 and thetop face of the belt 13, which in turn is supported on the top faces ofthe blocks 10, 11 and 12 successively. The tube 15 is maintained tightlyin contact Wiith the sheet 16 by the springs or the resilient strips 21.

The arrangement of FIG. 1 is advantageous because of the time factorsinvolved. Thus, while one assembly is at the heating station B, apreviously heated assembly may be at the cooling station at C, whileanother assembly is being prepared at station A. When the belt 13 movesto the right, that assembly which has been heated at B will be moved toC for cooling and since the cooling cycle takes only about two minutes,a new assembly can then be placed at C so that when the belt moves backtoward the left, the new assembly will move to the heating station Bwhile the just heated assembly will move to the cooling station at A.Obviously, this greatly increases the productive capacity of themachine.

The practice of the invention as herein described will produce anexcellent joint bond from the mechanical standpoint and from the heattransfer standpoint, and the aluminum sheet will retain is high degreeof flatness without distortion. If there should be a departure fromflatness as the assembly cools down to room temperature due to thedifference in thermal coefficient of expansion between sheet and tube,such departure from flatness will take the form of a long radius uniformcamber in one direction which can be removed later by a singlestraightening operation so as to leave the sheet substantially flatwithout wrinkles, undulations or other evidence of localized distortion.

It Will be understood that while the invention has been describedparticularly with respect to bonding tubing to a sheet, it is alsoadaptable to the securing of any sort of stiffening elements of the sameor different metal to one face of a sheet where it is desired tomaintain the flatness of the sheet.

It will be understood that various modifications may be made and that nolimitation not specifically set forth in the claims is intended orshould be implied.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. The method of securing an elongated metallic member to one face of aflat sheet of metal, while maintaining the flatness of said sheet ofmetal, which includes the steps of:

(a) laying an elongated strip of a bonding material, of lower meltingpoint than said sheet and member, on said sheet of metal along thelocation Where said member is to be secured;

(b) laying said member in position in the location Where it is to besecured, in contact with said strip;

(c) clamping said sheet, over substantially the entire area thereofwhich is not occupied by said member, under a uniform pressure;

(d) maintaining the positional relationship between said member, sheetand strip while continuously exerting pressure on said member; andconcurrently heating the assembly of member, sheet and strip to atemperature above the melting point of said strip but below the meltingpoint of said sheet and member; and

(e) cooling said assembly to a temperature substantially above 212 F.and below the hardening point of said strip until said strip hashardened and said member has thus been secured to said sheet.

2. The method of claim 1, wherein said member is a tube.

3. The method of claim 1, wherein said sheet is of aluminum, and saidmember is of copper tubing.

4. The method of claim 1 wherein said bonding material is a syntheticresin adhesive.

5. The method of claim 1 wherein said bonding material is a strip offluxed solder.

6. The method according to claim 5, wherein said fiuxed solder is in theform of a paste of powdered solder and flux and said paste is applied tosaid sheet by screen printing.

7. The method of claim 2, wherein said bonding material is a syntheticresin adhesive.

8. The method of claim 2, wherein said bonding material is a syntheticresin adhesive, applied to said sheet by screen printing.

9. Th method of claim 2, wherein said bonding material is a fluXedsolder.

10. The method of claim 9, wherein said fiuxed solder is in the form ofa paste of powdered solder and flux and said paste is applied to saidsheet by screen printing.

11. The method of claim 2, wherein said sheet is of aluminum, saidtubing is of copper, and said bonding material is a fiuxed solder andthe heating temperature is about 510 F. maintained for about threeminutes, with said uniform pressure being about 0.65 p.s.i., and saidcooling temperature is about 300 F. maintained for about two minutes.

References Cited UNITED STATES PATENTS 2,332,368 10/1943 Burtenshaw29-487 2,423,870 7/ 1947 Blessing. 2,627,010 1/1953 Matteson et al.29-50l X 3,151,591 10/1964 Burns et a1. 29-493 X 3,189,978 6/1965Stetson 29--626 X 3,382,561 5/1968 Swick et a1. 29-402 FOREIGN PATENTS609,909 12/1960" Canada.

CHARLIE T. MOON, Primary Examiner D. C. REILEY, Assistant Examiner U.S.Cl. X.R.

